Whether macrophages kill cells is determined by programmed death (apoptosis). When cells undergo apoptosis, they will send an "eat me" signal to macrophages, while active cells will send out a "rejection" signal, thus ensuring the effective removal of apoptotic cells. In the above process, the cluster of differentiation 31 (CD31) on the active cell membrane plays an important role in anti-phagocytosis. Exosomes are natural multifunctional carriers that can encapsulate and deliver various living substances. Although the composition of the cell membrane makes exosomes have high biocompatibility and low immunogenicity, it is inevitable that some exosomes entering the body cannot escape the fate of being cleared by macrophages as immunogens. Excitingly, with the anti-phagocytic properties of CD31, some researchers have proposed to modify CD31 on therapeutic exosomes to avoid triggering harmful immune responses. Creative Biolabs has always focused on developing the potential of exosomes as a new generation of drug delivery system and can produce CD31-expressed exosomes for customers to help the transformation of exosome drugs.

CD31 Overview

CD31, also known as platelet and endothelial cell adhesion molecule 1, is a type I transmembrane glycoprotein with a relative molecular weight of 130 kDa, which belongs to the C2 subgroup of the immunoglobulin superfamily in the cell adhesion molecule (CAM) family. In particular, CD31 is mainly involved in the mutual recognition and binding between the same CAM molecules on the surface of two adjacent cells, so one of the co-receptors of CD31 is itself. Studies have found that, as an adhesion molecule, CD31 is expressed on the surface of endothelial cells, circulating platelets, monocytes, neutrophils, certain T cell subsets, and certain tumor cells. Functionally, CD31 is involved in the regulation of various biological processes such as leukocyte migration, cell proliferation, apoptosis, and tumor metastasis. In the process of inhibiting apoptosis, the homologous binding of CD31 achieves its purpose of inhibiting apoptosis by activating or inhibiting signaling proteins in the signaling pathway, such as Akt, Bcl-2, Bcl-X, caspase, p38/JNK, and MAPK. CD31-mediated inhibition of apoptosis allows active cells to selectively output "dissociation" signals, and macrophages can distinguish between apoptotic cells and active cells based on this signal to ensure the survival of active cells. Therefore, CD31 is a cell membrane protein with anti-phagocytic function.

Featured CD31 Modification Service at Creative Biolabs

Creative Biolabs has been improving the exosome surface functionalization platform around customer needs and following up on exosome research progress, and can provide customers with two technical services to design CD31-expressed exosomes. On the one hand, our professional technicians can integrate CD31 into the exosome membrane protein through strict and complex genetic operations, so that the exosomes produced by the donor cells have the ability to escape from the immune system. On the other hand, the connection mediators are modified on the surface of exosomes and CD31 respectively, and then through covalent bonding (such as click chemistry and protein ligase) or non-covalent bonding (such as electrostatic interaction, hydrophobic interaction, receptor-ligand interaction, nucleic acid aptamer-based surface modification, anchor peptide modification) to attach CD31 to the surface of exosomes.

Fig.1 Approaches for engineering exosomes displaying targeting ligands.^1,2

Creative Biolabs has established a leading functionalized exosome development system, which can construct surface functionalized exosomes for customers. In order to better deliver results to customers, we can also provide exosome isolation and identification services before engineering, exosome loading services and targeted modification services during engineering, and efficiency verification and in vivo and in vitro functions research services after engineering. If you want to make therapeutic exosomes less immunogenic, please contact us with your ideas and needs. Our professional sales Manager and technical supporter will formulate the most optimized plan for you.

References

1. Liang, Y.; et al. Engineering exosomes for targeted drug delivery. Theranostics. 2021, 11(7):3183-3195.
2. under Open Access license CC BY 4.0, without modification.

• App1-Expressed Exosome Modification
• β₂M-Expressed Exosome Modification
• CD24-Expressed Exosome Modification
• CD44-Expressed Exosome Modification
• CD47-Expressed Exosome Modification
• DHMEQ-Expressed Exosome Modification
• PD-L1-Expressed Exosome Modification